I am not sure what's going on here. This doesn't seem to happen with the rocks, and small scenes I export, but with large terrains, when viewed from a distance there is like a patchwork of dotted lines. But when you get closer, they start to disappear, at the cost of giant polygons showing with bad shading. The dots even stick OFF the obejct when viewed from the side (though not sure if that's just AA sampling).
Anyone encountered this? I tried to subdivide it and recalculated all the normals, and the object was welded.